WASHINGTON (AP) – Hillary Clinton and Bernie Sanders are in a tug-of-war over who’s the best standard-bearer for progressive values as they road-test lines of argument for the first one-on-one debate of the Democratic presidential campaign.

The two candidates are tussling over who is more committed to – and capable of – carrying out a liberal agenda on health care, income inequality, worker rights and more.

Sanders is favored in New Hampshire’s first-in-the-nation primary. On the eve of Thursday night’s debate, he says Clinton’s record is “just not progressive” on any number of issues, including her vote as a senator to authorize the war in Iraq.

Clinton calls that a “low blow,” and presses her counter-argument that she’s the candidate with the ability to actually implement progressive changes.

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